Power lift gate actuator

ABSTRACT

A liftgate actuating assembly is disclosed for moving a liftgate of a motor vehicle between open and closed positions. The liftgate actuating assembly includes a motor that is fixedly secured to the motor vehicle. The motor has an output shaft capable of bi-directional rotation. A drive gear rotates about a drive shaft and is operatively connected to the output shaft to be rotated thereby. A cable drum is rotatably mounted to the drive shaft. The cable drum is coupled to the drive gear and is rotated thereby. The cable drum includes a cable wrapped thereabout between a drum end fixedly secured to the cable drum and a liftgate end fixedly secured to the liftgate. The cable is used to retract the liftgate from the open position to the closed position. A linkage is operatively connected to the drive gear. The linkage is from a retracted position to an extended position such that the linkage forces the liftgate from the closed position to the open position when the linkage moves from the retracted position to the extended position. The linkage includes a slot that provides lost motion within the linkage. This allows the liftgate to be move manually to the closed position without the motor being activated.

FIELD OF THE INVENTION

The invention relates to a system liftgate for a motor vehicle. Inparticular, the invention relates to an actuator used to assist in themovement of the liftgate of the motor vehicle between open and closedpositions.

DESCRIPTION OF THE RELATED ART

As motor vehicles characterized by their utility become a mainstreamchoice, consumers demand certain luxuries primarily associated withpassenger cars, either due to their inherent design and/or size. One ofthe features desired by consumers is the automated movement of suchitems as sliding doors and liftgates. While features providing automatedmotion are available, they are often cumbersome and add undue weight tothe motor vehicle.

U.S. Pat. No. 6,318,025 discloses one such device. This patent disclosesa system for power operating a liftgate. The liftgate utilizes a gasspring strut counterbalance system to aid in the opening of the liftgateonce the opening has begun. The power operating system includes at leastone drive unit that includes a reversible electric motor, a spool drivenby the electric motor, a flexible belt that has one end attached to thespool and an opposite end attached to the liftgate, and a push memberthat is driven by the electric motor between a retracted position and anextended position. To raise liftgate from the closed position to theopen position, the bottom of liftgate 12 is unlatched and motor isenergized to rotate an output shaft counterclockwise. This engagesoverrunning clutches and drives sprockets counter clockwise to extendthe push member, which pushes the liftgate to a partially open position.When the liftgate opens a predetermined amount, the opening force of thegas spring struts completes the opening of the liftgate to the fullyopen position shown in FIGS. 1 and 4. During this opening movement, thebelt is payed off the spool by the freewheeling of spool 28 when beingpulled by the opening tailgate.

To close the liftgate, the motor is energized to rotate the output shaftclockwise. This engages overrunning clutch and drives drum clockwise towind the web onto the spool, which pulls the liftgate to the closedposition. The closing liftgate also retracts the push member. The pushmember can be retracted because the freewheeling clutch allows the pushmember to move with respect to the output shaft. This power operatingsystem requires a plurality of clutches to make operate in bothautomatic and manual modes.

SUMMARY OF THE INVENTION

A liftgate actuating assembly is disclosed for moving a liftgate of amotor vehicle between open and closed positions. The liftgate actuatingassembly includes a motor that is fixedly secured to the motor vehicle.The motor has an output shaft capable of bi-directional rotation. Adrive gear rotates about a drive shaft and is operatively connected tothe output shaft to be rotated thereby. A cable drum is rotatablymounted to the drive shaft. The cable drum is coupled to the drive gearand is rotated thereby. The cable drum includes a cable wrappedthereabout between a drum end fixedly secured to the cable drum and aliftgate end fixedly secured to the liftgate. The cable is used toretract the liftgate from the open position to the closed position. Alinkage is operatively connected to the drive gear. The linkage is froma retracted position to an extended position such that the linkageforces the liftgate from the closed position to the open position whenthe linkage moves from the retracted position to the extended position.The linkage includes a slot that provides lost motion within thelinkage. This allows the liftgate to be move manually to the closedposition without the motor being activated.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the invention will be readily appreciated as the samebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

FIG. 1 is a perspective view of one embodiment of the invention in amotor vehicle, partially cut away;

FIG. 2 is a perspective view of the invention with a portion of thehousing removed;

FIG. 3 is a perspective view of the invention with a portion of thehousing removed; and

FIG. 4 is a perspective view of the invention with a rod retracted dueto manual closure of the liftgate; and

FIG. 5 is a schematic drawing of one embodiment of the control circuitincorporated by the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the Figures, a liftgate actuating assembly is generallyindicated at 10. The liftgate actuating assembly 10 is mounted to a rearpillar 12 of the motor vehicle 14 adjacent an opening 15 in the motorvehicle 14. The liftgate actuating assembly 10 includes a housing 16having a base 18 that is fixedly secured to the rear pillar 12. Theliftgate actuating assembly 10 moves a liftgate 20 between its closedposition and its open position, shown in FIG. 1. More specifically, theliftgate actuating assembly 10 initiates movement of the liftgate 20away from its closed position and completely returns the liftgate 20 tothe closed position from the open position. The liftgate actuatingassembly 10 does not completely move the liftgate 20, but initiates themovement thereof.

The liftgate actuating assembly 10 is connected to an electrical sourceand receives power therefrom. A motor 22 receives the electric power andconverts it into rotational motion. The motor 22 rotates an output shaft24. The output shaft 24 is operatively connected to a drive gear 26. Adrive transmission 28, including a plurality of gears (not shown)extends between the output shaft 24 and the drive gear 26 to facilitatethe proper force and direction of the rotational power that is to bereceived by the drive gear 26. The drive gear 26 rotates about a driveshaft 30. A roller bearing 32 is fixedly secured to the drive gear 26and will be discussed in greater detail subsequently.

The liftgate actuating assembly 10 also includes a cable drum 34. Thecable drum 34 is rotatably connected to the drive shaft 30 of the drivegear 26. More specifically, the cable drum 34 and the drive gear 26 arecoaxial. The cable drum 34 and the drive gear 26 are coupled and rotatein unison at times. At other times, the drive gear 26 and the cable drum34 are not coupled, allowing the cable drum 34 to rotate independentlyof the drive gear 26.

A cable 36 extends between a drum end (not shown) and a liftgate end 40.The drum end is fixedly secured to the cable drum 34 whereas theliftgate end 40 is fixedly secured to the liftgate 20. The cable 36 issubstantially wrapped around the cable drum 34 when the liftgate 20 isin its closed position.

The liftgate actuating assembly 10 includes a connecting device,generally shown at 42. The connecting device is a linkage 42 thatincludes a plurality of links 44, 46. In another embodiment, theconnecting device 42 may include a second cable (not shown) that isconfigured to initiate the opening of the liftgate 20.

In the embodiment shown in the Figures, the linkage 42 has two elements,a rod 44 and a curvilinear arm 46. The curvilinear arm 46 is pivotallysecured with respect to the housing 16. In one embodiment, thecurvilinear arm 46 may pivot about an axle in the drive transmission 28.A second end 48 of the curvilinear arm 46 is connected to the rod 44.The rod 44 is generally linear and defines a slot 50 that extends alonga portion thereof. A pin, represented by its head 51, extends out fromthe curvilinear arm 46 perpendicularly thereto. The pin 51 is receivedby the slot 50 allowing the pin 51 to travel therealong. Therefore, lostmotion is possible between the second end 48 of the curvilinear arm 46and the rod 44.

Extending out from the second end 48 and the rod 44 are an arm mount 52and a rod mount 54, respectively. The arm 52 and rod 54 mounts areinterconnected by two springs 56. The two springs 56 minimize the lostmotion between the second end 48 and the rod 44.

A bias spring 58 is mounted between the rod mount 54 and the housing 16.The bias spring 58, partially cut away in FIG. 3, biases the rod 44 froma retracted position toward an extended position to facilitate theopening of the liftgate 20.

The rod 44 is extendable out of the housing 16. When the rod 44 movestoward its extended position, it abuts the liftgate 20 and forces theliftgate 20 out of its closed position and toward its open position.After the rod 44 is fully extended, lift assist struts 60 move theliftgate 20 to its open position. The lift assist struts 60 eliminatethe need for much of the length of the rod 44. More specifically, therod 44 need only to move the liftgate 20 a portion of the distance awayfrom its closed position before the lift assist struts 60 move theliftgate toward its open position without further assistance from anyother mechanism.

Referring to FIG. 4, an electrical control circuit is generallyindicated at 62. As is typical for circuits in the motor vehicleenvironment, the electrical control circuit 62 operates off a twelveVolt DC power source. The electrical control circuit 62 controls themotor 22 and a latch motor 64. The latch motor 64 automates the cinchingand unlatching of the liftgate 20.

The electrical control circuit 62 includes a park switch 66. The parkswitch 66 prevents the unlatching and movement of the liftgate 20 awayfrom its closed position when the motor vehicle 14 is not in a parkedstate with its transmission in a parked condition.

The other two inputs are received from a latch switch 68 and a userswitch 70. The latch switch 68 identifies whether a latch should beengaged or disengaged. The user switch 70 is a toggle switch allowingthe user to identify whether the liftgate 20 is to move from oneposition to another.

The electric control circuit 62 operates in two modes, open and closed.In the open mode, the latch state is ignored and a motor hold openswitch 72 prevents the motor 22 from cycling. This will be discussed ingreater detail subsequently.

In operation and starting with the liftgate 20 in its closed positionand cinched, the operator of the liftgate 20 toggles the user switch 70.The latch unlatches the liftgate 20 using the latch release motor 64.The motor 22 rotates the drive gear 26 which, in turn, moves the rollerbearing 32 thereabout. The roller bearing 32 abuts and moves thecurvilinear arm 46. Because the rod 44 and the curvilinear arm 46 arecoupled via the springs 56, the rod 44 is forced to move axially towardits extended position. A distal end 74 of the rod 44 abuts the liftgate20 and forces it out of its closed position toward its open position.Once moved sufficiently, the lift assist struts 60 become active andmove the liftgate 20 to its open position.

The cable 36 is tied to the liftgate 20 and unwraps from the cable drum34. The cable drum 34 moves independently of the drive gear 26 throughthis movement.

In this position, the liftgate 20 is in its open position and the rod 44is in its extended position. The slot 50 allows manual closure of theliftgate 20 without damaging the rod 44. More specifically, the slot 50allows for lost motion between the rod 44 and the curvilinear arm 46should the liftgate 20 be closed manually by allowing the pin 51 totravel along the slot 50, thus providing a sufficient amount of play toallow the rod 44 to retract into the housing 16 and avoid damage by andto the liftgate 20.

Upon toggling the user switch 70, the liftgate actuating assembly 10moves to close the liftgate 20. The motor 22 begins to move whichrotates the drive gear 26. The drive gear 26 engages the cable drum 34and begins to retract the cable 36 by having it wrap thereabout. Theroller bearing 32 does not move the curvilinear arm 46 nor the rod 44because the bias spring 58 prevents the retraction of the rod 44 untilthe liftgate 20 forces the distal end 74 back toward the housing 16. Thebias spring 58 does not prevent the closing of the liftgate 20 becausethe distal end 74 cannot touch the liftgate 20 until it approaches theliftgate actuating assembly 10 and the rod 44 is retractable onceengaged by the liftgate 20.

Upon closing, the latch switch 68 sends a signal through terminal 76 tothe latch control circuit (not shown) that cinches the latch preventingthe liftgate 20 from leaving its closed position. A timer circuit 78,triggered by a latch state relay 80, switches the control circuit 62between open and closed operation modes by operating the operation moderelay 82. The operation mode relay 82 is shown in its closed position,which allows the liftgate 20 to be opened. It other state is required toclose the liftgate 20.

The invention has been described in an illustrative manner. It is to beunderstood that the terminology, which has been used, is intended to bein the nature of words of description rather than of limitation. Manymodifications and variations of the invention are possible in light ofthe above teachings. Therefore, within the scope of the appended claims,the invention may be practiced other than as specifically described.

1. A liftgate actuating assembly for moving a liftgate of a motorvehicle between an open position and a closed position, said liftgateactuating assembly comprising: a motor fixedly secured to the motorvehicle, said motor having an output shaft capable of bi-directionalrotation; a drive gear rotatable about a drive shaft, said drive gearoperatively connected to said output shaft to be rotated thereby; acable drum rotatably mounted to said drive shaft, said cable drumcoupled to said drive gear to be rotated thereby, said cable drumincluding a cable wrapped thereabout between a drum end fixedly securedto said cable drum and a liftgate end fixedly secured to the liftgatefor retracting the liftgate from the open position to the closedposition; and a linkage operatively connected to said drive gear, saidlinkage movable from a retracted position to an extended position suchthat said linkage forces the liftgate from the closed position to theopen position when said linkage moves from said retracted position tosaid extended position, said linkage including a slot providing lostmotion within said linkage allowing the liftgate to be moved manually tothe closed position without said motor being activated.
 2. A liftgateactuating assembly as set forth in claim 1 wherein said linkage includesa curvilinear arm pivotally movable by said drive gear as said drivegear is driven by said motor to move said linkage to said extendedposition.
 3. A liftgate actuating assembly as set forth in claim 2wherein said linkage includes a rod having a distal end extending outfrom said liftgate actuating assembly and engagable with the liftgate.4. A liftgate actuating assembly as set forth in claim 3 wherein saidrod includes said slot.
 5. A liftgate actuating assembly as set forth inclaim 4 wherein said curvilinear arm includes an arm mount.
 6. Aliftgate actuating assembly as set forth in claim 5 wherein said rodincludes a rod mount disposed opposite said distal end.
 7. A liftgateactuating assembly as set forth in claim 6 including a spring mountedbetween said arm and rod mounts to bias said arm and rod mounts towardeach other.
 8. A liftgate assembly as set forth in claim 7 including ahousing covering said drive gear and cable drum.
 9. A liftgate assemblyas set forth in claim 8 including a bias spring extending between saidhousing and said rod mount to bias said rod out toward said extendedposition.
 10. A liftgate assembly as set forth in claim 9 including aroller bearing rotatably secured to said drive gear for abutting againstsaid curvilinear arm to force said curvilinear arm to move said rodtoward said extended position.
 11. A liftgate actuating assembly formoving a liftgate of a motor vehicle between an open position and aclosed position, said liftgate actuating assembly comprising: a motorfixedly secured to the motor vehicle, said motor having an output shaftcapable of bi-directional rotation; a drive gear rotatable about a driveshaft, said drive gear operatively connected to said output shaft to berotated thereby; a cable drum rotatably mounted to said drive shaft,said cable drum coupled to said drive gear to be rotated thereby, saidcable drum including a cable wrapped thereabout between a drum endfixedly secured to said cable drum and a liftgate end fixedly secured tothe liftgate for retracting the liftgate from the open position to theclosed position; and a connecting device operatively connected to saiddrive gear, said connecting device movable from a retracted position toan extended position such that said connecting device forces theliftgate from the closed position to the open position when saidconnecting device moves from said retracted position to said extendedposition.
 12. A liftgate assembly for selectively opening and closing anopening in a motor vehicle, said liftgate assembly comprising: aliftgate pivotally secured to the motor vehicle, said liftgate movablebetween a closed position over the opening and an open position awayfrom the opening providing access to the motor vehicle; a motor fixedlysecured to the motor vehicle and disposed adjacent the opening, saidmotor having an output shaft capable of bi-directional rotation; a drivegear rotatable about a drive shaft, said drive gear operativelyconnected to said output shaft to be rotated thereby; a cable drumrotatably mounted to said drive shaft, said cable drum coupled to saiddrive gear to be rotated thereby, said cable drum including a cablewrapped thereabout between a drum end fixedly secured to said cable drumand a liftgate end fixedly secured to the liftgate for retracting theliftgate from the open position to the closed position; and a linkageoperatively connected to said drive gear, said linkage movable from aretracted position to an extended position such that said linkage forcesthe liftgate from the closed position to the open position when saidlinkage moves from said retracted position to said extended position,said linkage including a slot providing lost motion within said linkageallowing the liftgate to be moved manually to the closed positionwithout said motor being activated.
 13. A liftgate actuating assembly asset forth in claim 12 wherein said linkage includes a curvilinear armpivotally movable by said drive gear as said drive gear is driven bysaid motor to move said linkage to said extended position.
 14. Aliftgate actuating assembly as set forth in claim 13 wherein saidlinkage includes a rod having a distal end extending out from saidliftgate actuating assembly and engagable with the liftgate.
 15. Aliftgate actuating assembly as set forth in claim 14 wherein said rodincludes said slot.
 16. A liftgate actuating assembly as set forth inclaim 15 wherein said curvilinear arm includes an arm mount.
 17. Aliftgate actuating assembly as set forth in claim 16 wherein said rodincludes a rod mount disposed opposite said distal end.
 18. A liftgateactuating assembly as set forth in claim 17 including a spring mountedbetween said arm and rod mounts to bias said arm and rod mounts towardeach other.
 19. A liftgate assembly as set forth in claim 18 including ahousing covering said drive gear and cable drum.
 20. A liftgate assemblyas set forth in claim 19 including a bias spring extending between saidhousing and said rod mount to bias said rod out toward said extendedposition.